Electric extension plug



May 8, 1928. 1,669,193

J. A. FOURNEY ELECTRIC EXTENSION PLUG Filed Nov. 9,1922

; INVENTOR. Joh A.F ume W HIS ATTORNEY Patented May s, 1928.

UNITED STATESPATENT OFFICE. 7

JOHN A. Fouim'EY, 0F OAKLAND, cALImRN A.

ELECTRIC Extension rune.

Application filed November My invention relates broadly to plugs adapted to be 'fitted inthe usual screw-' threaded electricfixture socket so as :to connect anelectric-conductor thereto, and relates more particularly to plugs'of this character which are adapted to be connected toor disconnected from said type or socket by ion gitudinal movement rather than rotative.

An object of the invention is to provide a plug of the particular character described which will permit quick action both in connectlng and disconnecting the plug, and at the same time enable the plug to be firmly held in the socket and proper contact or the conductors maintained even when the connected plug is sulnected to considerable vibration and rough handling. v Another object is to provide an extremely simple plug of the character described and one in which the various electric conductors are so arranged that no short circuiting thereof can be effected. v,

The invention possesses otherobjects and features of advantage, some of which, with the foregoing, will be set forth in the follow ing description of the preferred formjof my invention which is illustrated in the drawings accompanying and forming part of'the specification.

as I may adopt varationsof the preferred form within the scope oi. my invention as set forth in the claims. i

Referring to said drawings:

Figure l is a perspective view of the plug.

Fi 'ure 2 is a lon itijulinal sectional View a: I a: I

thereof.

Figure 3 is a longitudinal section view of the plug showing it engaged in the fixture socket, the section being taken through a different portion of the plug than that shown in Figure 2.-

Figure 4 is a perspective view of the releasable retaining lever of the plug. I

Figure 5 is a transverse section of the plug taken on the line 5-5 of Figure 3.

Briefly expressed the plug in thepreferred embodiment of the invention comprises a block formed of an insulating material, a fixed contact at one side of the plug adapted to project into the socket threads and connected to one of a pair of electric conductors, a longitudinally-movable spring-pressed contact extending from one end of the block It is to be understood that I do not limit myself to the showing. made by the said drawings and description,-

9, 1922. Serial m1 599,320.

connected to'the other conductor of'said pair and adapted to engageithe central con tact postof the socket,-a lever fulcruined on said block having a tprojection' extending from'the other side 0 the latter arranged to resiliently engage in the socket threads, and manually operated means for retracting said projection so as to enable the blockto bemoved into or out of thesocke'.

A detailed description followsi The plug as here illustrated comprises a block 6 made oi? a si'iitableinsulating mate rial and having a reduced cylindrical portion 7 which is adapted to lit in the usual screwthreaded'opening 8 of the electricfixture socket 9. The unreduced portion 10 01" the plug is recessed and houses the ends of the electric conductors 12 and 13. An insulating shell'ld encloses the portion 10 and is secured to the perforated flange 16 through which the conductors extend. Fixed in the portion 7 of the plug and projecting outwardly from oneside thereof is'an. electrical contact 17 which is connectedto the conductor 12 by suitable means 18 arrangedwithin theblock; 'When the plug is engaged in the socket, the

contact 17 fitsbetween the threads 19 {of the socket andthereby makes electrical connec tion with the electric lead associated with, the metallic shell in which the threads 19 are formed.

Means are provided,.wh ich when the plug is insertedin' the socket, resiliently engage diametrical alignment with the contact '17.

By means of a tension spring 24 operative against the other lever arm, the lever extension 23. is'normally held extended from the block. In this manner when the plug is; engaged in the socket the extension 23 will engage between the threads 19 and thereby cooperate with the contact 17 to a hold the plug firmly secured in the socket, In order that the extension 23 may beretracted, such as when the plug is inserted in or removed from the socket, there is mounted in the block a. slidable rod 26 which when moved inwardly, against the last mentioned lever arm, rocks the lever and causes the extension to be withdrawn into the recess 22. 2

Means are provided for causing both the contact 17 and the projection 23 to be resiliently pressed against the lower face of the threads 19 when the plug hasbeen properly fitted into the socket. As here shownsaid means comprises a rod 28 which is slidable longitudinally in the block and projectsfrom the end 29 thereof. The rod is normally rctained in extended position by means of a spring 30. In use the plug is inserted far enough into the socket to cause the outer end of the rod to abut against the end face 33 of the socket with sufficient pressure to compress the spring 30. In this manner the members 17 and 23 will be forcibly pressed against the lower face of the threads and the plug will be rigidly held in the socket. In the present embodiment of the invention, the foregoing means is incidentally used as ameans for establishing contact between the conductor 13 and the center-post contact of the socket. By referring to Figure 2, it will be noted that the inner end of the rod is connected to the conductor 13, whereas the outer end thereof is provided with a laterally extending head which is adapted to engage the center contact of the socket when the plug is inserted in the socket. Rotation of the rod is preferably prevented by means of the pin 36 which depends from the head and engages an opening 37 formed in the block.

As clearly shown in Figure 5 the membersv 17 and 23 present wide segments in transverse section, thus enabling them to engage a comparatively large surface of the threads and thereby eliminating any tendency on the part of the plug to oscillate with respect to the socket when engaged therein.

The contacts 17 and. 28 as well as the lever 21 are separated by comparatively an electric conductor and arranged to engage in the socket threads, a contact member projecting from one end of said block and mounted therein for relative longitudinal movement with respect. thereto one end of .said contact being connected to another electric conductor, a spring encircling said movable contact member and urging the other end thereof outward from the block, a lever having a pro ection at the other side of said block adapted for 'engagementwith the socket threads, a spring normally pressQ and having an arm thereof providing a projection at the other'side of said block adapted for engagement with the socket threads, a spring operative against the other arm of said lever so as to hold said projection extended from the block, and a manually operable plunger arranged to engage said second lever arm so as to rock the lever to retract said projection.

3. An attachment plug for screw-threaded sockets, comprising a block formed of an insulating material, a contact member projecting from one side of said block arranged to engage the threads of the socket, a lever of the first class fulcrumed on said block and having an arm thereof provided with a projection normally disposed to engage socket threads oppositely of said contact member, a tension spring operative against the other arm of said lever to normally hold saidprojection in operative position, and a plunger manually operable against said second arm of the lever from said first side of the block to engage said lever so as to.

retract said projection.

In testimony whereof, I have hereunto set my hand at Oakland, this 21st day'of Oct. 1922.

JOHN A. FOURNEY. 

